Local optimization of electrode current densities

ABSTRACT

An end effector assembly for use with a bipolar forceps includes a pair of opposing first and second jaw members at least one of which being movable relative to the other to grasp tissue therebetween. Each jaw member includes a pair of spaced apart, electrically conductive tissue sealing surfaces. Each tissue sealing surface is adapted to connect to a source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue seal. The forceps also includes an insulator disposed between each pair of electrically conductive sealing surfaces and an electrically conductive cutting element disposed within each insulator and defining a geometrical configuration including a plurality of peaks having a period that is a multiple of an operating frequency of the electrosurgical energy. The cutting elements are adapted to connect to the source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue cut.

BACKGROUND

1. Technical Field

The following disclosure relates to an apparatus, system, and method for performing an electrosurgical procedure and, more particularly, to local optimization of electrode current densities utilizing electrode geometries.

2. Description of Related Art

It is well known in the art that electrosurgical generators are employed by surgeons in conjunction with electrosurgical instruments to perform a variety of electrosurgical surgical procedures (e.g., tonsillectomy, adenoidectomy, etc.). An electrosurgical generator generates and modulates electrosurgical energy which, in turn, is applied to the tissue by an electrosurgical instrument. Electrosurgical instruments may be either monopolar or bipolar and may be configured for open or endoscopic procedures.

Electrosurgical instruments may be implemented to ablate, seal, cauterize, coagulate, and/or desiccate tissue and, if needed, cut and/or section tissue. Typically, cutting and/or sectioning tissue is performed with a knife blade movable within a longitudinal slot located on or within one or more seal plates associated with one or more jaw members configured to receive a knife blade, or portion thereof. The longitudinal slot is normally located on or within the seal plate within a treatment zone (e.g., seal and/or coagulation zone) associated therewith. Consequently, the knife blade cuts and/or sections through the seal and/or coagulation zone during longitudinal translation of the knife blade through the longitudinal slot. In some instances, it is not desirable to cut through the zone of sealed or coagulated tissue, but rather to the left or right of the zone of sealed or coagulated tissue such as, for example, during a tonsillectomy and/or adenoidectomy procedure.

SUMMARY

According to an embodiment of the present disclosure, an end effector assembly for use with a bipolar forceps includes a pair of opposing first and second jaw members at least one of which being movable relative to the other to grasp tissue therebetween. Each jaw member includes a pair of spaced apart, electrically conductive tissue sealing surfaces. Each tissue sealing surface is adapted to connect to a source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue seal. The end effector assembly also includes an insulator disposed between each pair of electrically conductive sealing surfaces and an electrically conductive cutting element disposed within each insulator and defining a geometrical configuration including a plurality of peaks having a period that is a multiple of an operating frequency of the electrosurgical energy. The cutting elements are adapted to connect to the source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue cut.

According to another embodiment of the present disclosure, an end effector assembly for use with a bipolar forceps includes a pair of opposing first and second jaw members at least one of which being movable relative to the other from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. Each jaw member includes a pair of spaced apart, electrically conductive tissue sealing surfaces extending along a length thereof. Each tissue sealing surface is adapted to connect to a source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue seal. The end effector assembly also includes an insulator disposed between each pair of electrically conductive sealing surfaces and an electrically conductive cutting element disposed within the insulator of the first jaw member and in general vertical registration with an electrically conductive cutting element disposed within the insulator of the second jaw member. Each of the electrically conductive cutting elements includes a plurality of peaks offset from a plurality of peaks of the other cutting element. The number of peaks of at least one of the cutting elements is a function of a wavelength of an operating frequency of the electrosurgical energy. The cutting elements are adapted to connect to the source of electrosurgical energy to conduct electrosurgical energy through tissue held therebetween to effect a tissue cut. The cutting elements are inactive during tissue sealing and the pair of spaced apart electrically conductive sealing surfaces on the first jaw member are energized to a different potential from the corresponding pair of spaced apart electrically conductive sealing surfaces on the second jaw member such that electrosurgical energy can be transferred through the tissue to effect a tissue seal.

According to another embodiment of the present disclosure, a method of manufacturing an electrically conductive cutting element adapted to be coupled to an end effector assembly for effecting a tissue cut includes the steps of providing an electrically conductive electrode having a predetermined length and calculating a number of peaks along the predetermined length and a period based on a repetition of the peaks. The number of peaks is a function of an operating frequency of an energy source adapted to supply electrosurgical energy to the electrically conductive cutting element.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described hereinbelow with references to the drawings, wherein:

FIG. 1A is a right, perspective view of an endoscopic bipolar forceps in accordance with an embodiment of the present disclosure;

FIG. 1B is a left, perspective view of an open bipolar forceps in accordance with an embodiment of the present disclosure;

FIG. 2 is an enlarged view of the area of detail of FIG. 1B;

FIG. 3 is an enlarged, schematic end view of an electrode assembly according to an embodiment of the present disclosure; and

FIGS. 4A-4C are cross-sectional views taken along section line 4A, 4B, 4C-4A, 4B, 4C of FIG. 3 illustrating various geometric configurations of cutting elements according to various embodiments of the present disclosure.

DETAILED DESCRIPTION

For the purposes herein, vessel/tissue cutting or vessel/tissue division is believed to occur when heating of the vessel/tissue leads to expansion of intracellular and/or extra-cellular fluid, which may be accompanied by cellular vaporization, desiccation, fragmentation, collapse and/or shrinkage along a so-called “cut zone” in the vessel/tissue. By focusing the electrosurgical energy and heating in the cut zone, the cellular reactions are localized creating a fissure. Localization is achieved by regulating the vessel/tissue condition and energy delivery, which may be controlled by utilizing one or more of the various geometrical electrode configurations described herein. The cut process may also be controlled by utilizing a generator and feedback algorithm (and one or more of the hereindescribed geometrical configurations of the electrode assemblies) that increases the localization and maximizes the so-called “cutting effect”.

In general, the below-described factors contribute and/or enhance vessel/tissue division using electrosurgical energy. Each of the factors described below may be employed individually or in any combination to achieve a desired cutting effect. For the purposes herein, the term “cut effect” or “cutting effect” refers to the actual division of tissue by one or more of the electrical or electromechanical methods or mechanisms described below. The term “cutting zone” or “cut zone” refers to the region of vessel/tissue where cutting will take place. The term “cutting process” refers to steps that are implemented before, during, and/or after vessel/tissue division that tend to influence the vessel/tissue as part of achieving the cut effect.

For the purposes herein, the terms “tissue” and “vessel” may be used interchangeably since it is believed that the present disclosure may be employed to seal and cut tissue or seal and cut vessels utilizing the same principles described in the present disclosure.

By way of example and without limitation, factors that either alone or in combination play an important role in dividing tissue include: (1) localizing or focusing electrosurgical energy in the cut zone during the cutting process while minimizing energy effects to surrounding tissues; (2) focusing the current density in the cut zone during the cutting process; (3) creating an area of increased temperature in the cut zone during the cutting process (e.g., heating that occurs within the tissue or heating the tissue directly with a heat source); and (4) pulsing the energy delivery to influence the tissue in or around the cut zone.

Electrode assemblies described herein utilize various geometrical configurations of electrodes, cutting elements, insulators, partially conductive materials, and semiconductors to produce or enhance the cutting effect. In addition, by controlling or regulating the electrosurgical energy from the generator in any of the ways described above, tissue cutting may be initiated, enhanced, or facilitated within the tissue cutting zone.

For example, the geometrical configuration of the electrodes may be configured to produce a so-called “cut effect” that is directly related to the current density applied to a point in the tissue. The geometry of the electrodes may be configured such that the surface area ratios between the electrical poles focus electrical energy at the tissue. Moreover, optimization of the “cut effect” may be achieved by configuring the geometry of bipolar-type electrodes to include a specific number of peaks (see FIGS. 4A, 4B, and 4C) as a function of the operating frequency (e.g., the fundamental frequency) of the energy source used to produce the “cut effect”. More specifically, bipolar-type electrodes having peaks repeating at a particular period T (see FIG. 4A) and that period T is a multiple of the operating frequency of the energy being applied to tissue to produce the “cut effect”, the current density between the electrodes will be maximized, thereby optimizing the “cut effect”. The present disclosure provides for various electrode geometries configured in accordance with the operating frequency of the output energy and a method for calculating such geometric configurations as a function of the operating frequency of energy output for purposes of optimizing the “cut effect”.

Referring now to FIGS. 1A and 1B, FIG. 1A depicts a bipolar forceps 10 for use in connection with endoscopic surgical procedures and FIG. 1B depicts an open forceps 100 for use in connection with traditional open surgical procedures. For the purposes herein, either an endoscopic instrument or an open instrument may be utilized with the electrode assembly described herein. Different electrical and mechanical connections and considerations apply to each particular type of instrument, however, the novel aspects with respect to the electrode assembly and its operating characteristics remain generally consistent with respect to both the open or endoscopic designs.

FIG. 1A shows a bipolar forceps 10 for use with various endoscopic surgical procedures and generally includes a housing 20, a handle assembly 30, a rotating assembly 80, a switch assembly 70, and an electrode assembly 105 having opposing jaw members 110 and 120 that mutually cooperate to grasp, seal, and divide tubular vessels and vascular tissue. More particularly, forceps 10 includes a shaft 12 which has a distal end 16 dimensioned to mechanically engage the electrode assembly 105 and a proximal end 14 that mechanically engages the housing 20. The shaft 12 includes one or more mechanically engaging components that are designed to securely receive and engage the electrode assembly 105 such that the jaw members 110 and 120 are pivotable about a pivot pin 19 relative to one another to engage and grasp tissue therebetween.

The proximal end 14 of shaft 12 mechanically engages the rotating assembly 80 (not shown) to facilitate rotation of the electrode assembly 105. In the drawings and in the descriptions that follow, the term “proximal”, as is traditional, will refer to the end of the forceps 10 that is closer to the user, while the term “distal” will refer to the end that is farther from the user. Details relating to the mechanically cooperating components of the shaft 12 and the rotating assembly 80 are described in commonly-owned U.S. Pat. No. 7,156,846.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40. Fixed handle 50 is integrally associated with housing 20 and, handle 40 is movable relative to fixed handle 50 to impart movement of the jaw members 110 and 120 from an open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another, to a clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween. Switch assembly 70 is configured to selectively provide electrical energy to the electrode assembly 105.

Referring now to FIG. 1B, an open forceps 100 includes a pair of elongated shaft portions 112 a and 112 b each having a proximal end 114 a and 114 b, respectively, and a distal end 116 a and 116 b, respectively. The forceps 100 includes jaw members 120 and 110 which attach to distal ends 116 a and 116 b of shafts 112 a and 112 b, respectively. The jaw members 110 and 120 are connected about pivot pin 119 such that jaw members 110 and 120 pivot relative to one another from the first to second positions for treating tissue. The electrode assembly 105 is connected to opposing jaw members 110 and 120 and may include electrical connections through or around the pivot pin 119.

Each shaft 112 a and 112 b includes a handle 117 a and 117 b disposed at the proximal end 114 a and 114 b thereof which each define a finger hole 118 a and 118 b, respectively, therethrough for receiving a finger of the user. Finger holes 118 a and 118 b facilitate movement of the shafts 112 a and 112 b relative to one another that, in turn, pivot the jaw members 110 and 120 from the open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another to the clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween. A ratchet 130 is included for selectively locking the jaw members 110 and 120 relative to one another at various positions during pivoting.

As best seen in FIG. 1B, forceps 100 also includes an electrical interface or plug 200 that connects the forceps 100 to a source of electrosurgical energy, e.g., electrosurgical generator 500 (FIG. 1A). An electrical cable 210 extends from the plug 200 and securely connects the cable 210 to the forceps 100. Cable 210 is internally divided within the shaft 112 b to transmit electrosurgical energy through various electrical feed paths to the electrode assembly 105.

One of the shafts, e.g., 112 b, includes a proximal shaft connector/flange 121 that is configured to connect the forceps 100 to a source of electrosurgical energy (e.g., electrosurgical generator 500). More particularly, flange 121 mechanically secures electrosurgical cable 210 to the forceps 100 such that the user may selectively apply electrosurgical energy as needed.

As best shown in the schematic illustration of FIG. 2, the jaw members 110 and 120 of both the endoscopic version of FIG. 1A and the open version of FIG. 1B are generally symmetrical and include similar component features that cooperate to permit facile rotation about pivot 19, 119 to effect the grasping and sealing of tissue. Each jaw member 110 and 120 includes an electrically conductive tissue contacting surface 112 and 122, respectively, that cooperate to engage the tissue during sealing and cutting. At least one of the jaw members, e.g., jaw member 120, includes an electrically energizable cutting element 127 disposed therein, explained in detail below. Together and as shown in the various figure drawings described hereafter, the electrode assembly 105 includes the combination of the sealing electrodes 112 and 122 and the cutting element(s) 127.

The various electrical connections of the electrode assembly 105 are configured to provide electrical continuity to the tissue contacting surfaces 110 and 120 and the cutting element(s) 127 through the electrode assembly 105. For example, cable lead 210 may be configured to include three different leads, namely, leads 207, 208 and 209 that carry different electrical potentials. The cable leads 207, 208 and 209 are fed through shaft 112 b and connect to various electrical connectors (not shown) disposed within the proximal end of the jaw member 110 which ultimately connect to the electrically conductive sealing surfaces 112 and 122 and cuffing element(s) 127.

The various electrical connections from lead 210 are dielectrically insulated from one another to allow selective and independent activation of either the tissue contacting surfaces 112 and 122 or the cutting element 127. Alternatively, the electrode assembly 105 may include a single connector that includes an internal switch (not shown) to allow selective and independent activation of the tissue contacting surfaces 112, 122 and the cutting element 127.

As best seen in FIG. 3, an embodiment of the electrode assembly 105 is shown that is configured to effectively seal and cut tissue disposed between the sealing surfaces 112 and 122 and the cutting elements 127 of the opposing jaw members 110 and 120, respectively. More particularly and with respect to FIGS. 2 and 3, jaw members 110 and 120 include conductive tissue contacting surfaces 112 and 122, respectively, disposed along substantially the entire longitudinal length thereof (e.g., extending substantially from the proximal to distal end of the respective jaw member 110 and 120). In embodiments, tissue contacting surfaces 112 and 122 may be attached to the jaw members 110, 120 by stamping, by overmolding, by casting, by overmolding a casting, by coating a casting, by overmolding a stamped electrically conductive sealing plate, and/or by overmolding a metal injection molded seal plate.

With respect to FIG. 3, jaw members 110 and 120 both include an insulator or insulative material 113 and 123, respectively, disposed between each pair of electrically conductive sealing surfaces on each jaw member 110 and 120, i.e., between pairs 112 a and 112 b and between pairs 122 a and 122 b. Each insulator 113 and 123 is generally centered between its respective tissue contacting surface 112 a, 112 b and 122 a, 122 b along substantially the entire length of the respective jaw member 110 and 120 such that the two insulators 113 and 123 generally oppose one another.

At least one jaw member 110 and/or 120 includes an electrically conductive cutting element 127 disposed substantially within or disposed on the insulator 113, 123. As described in detail below, the cutting element 127 (in many of the embodiments described hereinafter) plays a dual role during the sealing and cutting processes, namely: 1) to provide the necessary gap distance between conductive surfaces 112 a, 112 b and 122 a, 122 b during the sealing process; and 2) to electrically energize the tissue along the previously formed tissue seal to cut the tissue along the seal. With respect to FIG. 3, the cutting elements 127 a, 127 b are electrically conductive, however, one or both of the cutting elements 127 a, 127 b may be made from an insulative material with a conductive coating disposed thereon or one (or both) of the cutting elements 127 a, 127 b may be non-conductive. In some embodiments, the distance between the cutting element(s) 127 a and the opposing cutting element 127 b (or the opposing return electrode in some cases) is within the range of about 0.008 inches to about 0.015 inches to optimize the cutting effect.

The general characteristics of the jaw members 110 and 120 and the electrode assembly 105 will initially be described with respect to FIG. 3 while the changes to the other embodiments disclosed herein will become apparent during the description of each individual embodiment. Moreover, FIG. 3 shows an electrical configuration and polarity during the cutting phase only. During the so called “sealing phase”, the jaw members 110 and 120 are closed about tissue and the cutting elements 127 a and 127 b form the requisite gap between the opposing sealing surfaces 112 a, 122 a and 112 b, 122 b. During activation of the sealing phase, the cutting elements 127 a and 127 b are not necessarily energized such that the majority of the current is concentrated between opposing sealing surfaces, 112 a and 122 a and 112 b and 122 b to effectively seal the tissue. In embodiments, stop members (not shown) may be employed to regulate the gap distance between the sealing surfaces in lieu of the cutting elements 127 a and 127 b. The stop members may be disposed on the sealing surfaces 112 a, 122 a and 112 b, 122 b, adjacent the sealing surfaces 112 a, 122 a and 112 b, 122 b or on the insulator(s) 113, 123.

In some embodiments, the cutting elements 127 a and 127 b are configured to extend from their respective insulators 113 and 123, respectively, and extend beyond the tissue contacting surfaces 112 a, 112 b and 122 a, 122 b such that the cutting elements 127 a and 127 b act as stop members (i.e., create a gap distance “G” (See FIG. 3) between opposing conductive sealing surfaces 112 a, 122 a and 112 b, 122 b) that as mentioned above, promotes accurate, consistent, and effective tissue sealing. The cutting elements 127 a and 127 b also prevent the opposing tissue contacting surfaces 112 a, 122 a and 112 b, 122 b from touching to eliminate the chances of the forceps 10, 100 shorting during the sealing process.

With respect to FIG. 3, the conductive cutting elements 127 a and 127 b are oriented in opposing, vertical registration within respective insulators 113 and 123 of jaw members 110 and 120. In some embodiments, the cutting elements 127 a and 127 b are substantially dull so as to not inhibit the sealing process (i.e., premature cutting) during the sealing phase of the electrosurgical activation. In other words, the surgeon is free to manipulate, grasp and clamp the tissue for sealing purposes without the cutting elements 127 a and 127 b mechanically cutting into the tissue. Moreover, in this instance, tissue cutting can only be achieved through either: 1) a combination of mechanically clamping the tissue between the cutting elements 127 a and 127 b and applying electrosurgical energy from the cutting elements 127 a and 127 b, through the tissue and to the return electrodes, i.e., the electrically conductive tissue contacting surfaces 112 b and 122 b as shown in FIG. 3; or 2) applying electrosurgical energy from the cutting elements 127 a and 127 b through the tissue and to the return tissue contacting surfaces 112 b and 122 b.

In some embodiments, the geometrical configuration of the cutting elements 127 a and 127 b may, at least in part, determine the overall effectiveness of the tissue cut. Certain geometries of the cutting elements 127 a and 127 b may create higher areas of current density than other geometries. Moreover, the spacing of the return electrodes 112 b and 122 b to these current density affects the electrical fields through the tissue. Therefore, by configuring the cutting elements 127 a and 127 b and the respective insulators 113 and 123 within close proximity to one another, the current density remains high which is ideal for cutting and the instrument will not short due to accidental contact between conductive surfaces. The relative size of the cutting elements 127 a and 127 b and/or the size of the insulator 113 and 123 may be selectively altered depending upon a particular or desired purpose to produce a particular surgical effect.

Turning now to the embodiments of the electrode assembly 105 as disclosed herein, FIG. 3 as mentioned above includes first and second jaw members 110 and 120 having an electrode assembly 105 disposed thereon. More particularly, the electrode assembly 105 includes first electrically conductive sealing surfaces 112 a and 112 b each disposed in opposing registration with second electrically conductive sealing surfaces 122 a and 122 b on jaw members 110 and 120, respectively. Insulator 113 electrically isolates sealing surfaces 112 a and 112 b from one another allowing selective independent activation of the sealing surfaces 112 a and 112 b. Insulator 123 separates sealing surfaces 122 a and 122 b from one another in a similar manner thereby allowing selective activation of sealing surfaces 122 a and 122 b.

Each insulator 113 and 123 is set back a predetermined distance between the sealing surfaces 112 a, 112 b and 122 a, 122 b to define a recess 149 a, 149 b and 159 a, 159 b, respectively, that as mentioned above, affects the overall current densities between the electrically activated surfaces during both the sealing and cutting phases. Cutting element 127 a is disposed within and/or deposited on insulator 113 and extends inwardly therefrom to extend beyond the sealing surfaces 112 a, 112 b by a predetermined distance.

During sealing, the opposing sealing surfaces 112 a, 122 a and 112 b, 122 b are activated to seal the tissue disposed therebetween to create two tissue seals on either side of the insulators 113 and 123. During the cutting phase, the cutting elements 127 a and 127 b are energized with a first electrical potential “+” and the right opposing sealing surfaces 112 b and 122 b are energized with a second electrical potential “−”. This creates a concentrated electrical path between the potentials “+” and “−” through the tissue to cut the tissue between the previously formed tissue seals. Once the tissue is cut, the jaw members 110 and 120 are opened to release the two tissue halves.

With reference to FIGS. 4A, 4B, and 4C, to maximize the current density between cutting elements 127 a and 127 b and, thereby optimize the “cutting effect”, the geometry of the cutting elements 127 a and 127 b may be configured to include a plurality of peaks 131 separated by valleys 133 interposed therebetween to define waveforms having a period T (illustrated, for example, in FIG. 4A). In the illustrated embodiments of FIGS. 4A, 413, and 4C, the waveforms defined by cutting elements 127 a, 127 b are off-set from one another such that the peaks 131 of cutting element 127 a complement the valleys 133 of cutting element 127 b and vice-versa. The various peak 131 and valley 133 configurations depicted by FIGS. 4A, 4B, and 4C are intended to illustrate the concept that the period T of the waveforms defined by cutting element 127 a and/or 127 b is configured as a function of the operating frequency of the output energy from the energy source (e.g., generator 500) to maximize the current density between cutting elements 127 a and 127 b, thereby optimizing the “cut effect”. The geometric configurations depicted by FIGS. 4A, 4B, and 4C are illustrative only in that any suitable geometric shape of peaks 131 and/or valleys 133 may be used to maximize current density between cutting elements 127 a and 127 b in the manner described hereinabove and hereinafter.

The relationship between the operating frequency of the energy source and the geometric configuration of the cutting element(s) 127 a and/or 127 b is illustrated by the following set of equations: λ=f/v;  (1)

wherein λ is the wavelength of the waveform defined by cutting element(s) 127 a and/or 127 b; f is the operating frequency (or fundamental frequency) of the output energy of the energy source (e.g., generator 500); and v is the velocity of the output energy.

Equation (1), in turn, is utilized to yield equation d=λ/x;  (2)

wherein d is a distance between any two points along the waveform defined by cutting element(s) 127 a and/or 127 b that may be used to define the period T of the waveform; and x is the number of peaks 131 along the waveform.

Equations (1) and (2), in turn, are utilized to yield equation d*x=f/v;  (3)

Equations (1) and (3), in turn, are utilized to yield equation d=λ/x;  (4)

wherein the number x of peaks 131 can be varied as necessary to yield the appropriate number of peaks 131 for a given length L of cutting element(s) 127 a and/or 127 b.

Utilizing equation (4), the current density between cutting elements 127 a and 127 b may be maximized by configuring each cutting element 127 a and/or 127 b to include the appropriate number x of peaks 131 for a given length L of cutting element 127 a and/or 127 b as a function of the wavelength λ of the operating frequency of the energy source (e.g., generator 500) used to produce the “cut effect”. In this manner, the “cut effect” produced by application of energy to tissue via cutting element(s) 127 a and/or 127 b is optimized.

When manufacturing cutting element(s) 127 a and/or 127 b, the “cut effect” may be optimized by using equation (4) to calculate the appropriate number of peaks x for a given length L of cutting element(s) 127 a and/or 127 b as a function of the operating frequency f of the energy source associated with forceps 10, 100. Conversely, the “cut effect” may be optimized by using equation (4) to calculate the appropriate operating frequency f as a function of the geometric configuration of cutting element(s) 127 a and/or 127 b (e.g., the number of peaks x for a given length L) and adjusting (e.g., discretely) the operating frequency of the energy source (e.g., generator 500) accordingly. That is, for example, a suitable control mechanism (not shown) may be disposed on the generator 500 to allow a user to selectively adjust the operating frequency of the generator 500 in accordance with the geometric configuration of a cutting element and/or electrode of an instrument connected to the generator 500 for purposes of sealing and/or cutting tissue utilizing the energy output of the generator 500.

In some embodiments, the current density and/or current concentration around the cutting elements 127 a and 127 b is based upon the particular geometrical configuration of the cutting elements 127 a and 127 b and the cutting elements' 127 a and 127 b proximity to the return electrodes, i.e., tissue contacting surfaces 112 b and 122 b.

In addition, the cutting element(s) 127 a (and/or 127 b) may be independently activated by the surgeon or automatically activated by the generator once sealing is complete. A safety algorithm may be employed to assure that an accurate and complete tissue seal is formed before cutting. An audible or visual indicator (not shown) may be employed to assure the surgeon that an accurate seal has been formed and the surgeon may be required to activate a trigger (or deactivate a safety) before cutting. For example, a smart sensor or feedback algorithm (not shown) may be employed to determine seal quality prior to cutting. The smart sensor or feedback loop may also be configured to automatically switch electrosurgical energy to the cutting element(s) 127 a (and/or 127 b) once the smart sensor determines that the tissue is properly sealed. In embodiments, the electrical configuration of the electrically conductive sealing surfaces 112 a, 112 b and 122 a, 122 b may be automatically or manually altered during the sealing and cutting processes to effect accurate and consistent tissue sealing and cutting.

The various geometrical configurations and electrical arrangements of the aforementioned electrode assemblies allow the surgeon to initially activate the two opposing electrically conductive tissue contacting surfaces and seal the tissue and, subsequently, selectively and independently activate the cutting element and one or more tissue contacting surfaces to cut the tissue utilizing the various above-described and shown electrode assembly configurations. Hence, the tissue is initially sealed and thereafter cut without re-grasping the tissue.

However, the cutting element and one or more tissue contacting surfaces may also be activated to simply cut tissue/vessels without initially sealing. For example, the jaw members may be positioned about tissue and the cutting element may be selectively activated to separate or simply coagulate tissue. This type of alternative embodiment may be particularly useful during certain endoscopic procedures wherein an electrosurgical pencil is typically introduced to coagulate and/or dissect tissue during the operating procedure.

A switch (e.g., switch assembly 70 shown in FIG. 1A) may be employed to allow the surgeon to selectively activate one or more tissue contacting surfaces or the cutting element independently of one another. This allows the surgeon to initially seal tissue and then activate the cutting element by simply actuating the switch.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

What is claimed is:
 1. An end effector assembly for use with a bipolar forceps, the end effector assembly comprising: a pair of opposing first and second jaw members at least one of which being movable relative to the other from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween; each jaw member including a pair of spaced apart, electrically conductive tissue sealing surfaces extending along a length thereof, each tissue sealing surface adapted to conduct electrosurgical energy through tissue held therebetween to effect a tissue seal; an insulator disposed between each pair of electrically conductive sealing surfaces; and an electrically conductive cutting element disposed within each insulator and defining a geometrical configuration of a recurring pattern including a plurality of peaks, the recurring pattern having a period that is a multiple of an operating frequency of electrosurgical energy passed therethrough, the cutting elements adapted to electrosurgically effect a tissue cut.
 2. An end effector assembly according to claim 1, wherein a number of the plurality of peaks is calculated based on a repetition of the peaks for a predetermined length of the electrically conductive cutting elements.
 3. An end effector assembly according to claim 1, wherein the number of peaks for a given length of the cutting elements is a function of a wavelength of the operating frequency of the electrosurgical energy.
 4. An end effector assembly according to claim 1, wherein the geometric configuration of the cutting element of the first jaw member is off-set from the geometric configuration of the cutting element of the second jaw member.
 5. An end effector assembly according to claim 1, wherein the plurality of peaks of the cutting element of the first jaw member is configured to complement a plurality of valleys interposed between the plurality of peaks of the cutting element of the second jaw member.
 6. A end effector assembly according to claim 1, wherein the electrically conductive cutting element disposed within the insulator on the first jaw member is disposed in general vertical registration to the insulator on the second jaw member; wherein the electrically conductive cutting element extends from the electrically conductive tissue sealing surface on the first jaw member towards the electrically conductive tissue sealing surface on the second jaw member to create a gap between the electrically conductive tissue sealing surfaces when the jaw members close for sealing tissue.
 7. An end effector assembly according to claim 1, wherein the cutting elements are disposed in vertical registration relative to one another.
 8. An end effector assembly for use with a bipolar forceps, the end effector assembly comprising: a pair of opposing first and second jaw members at least one of which being movable relative to the other from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween; each jaw member including a pair of spaced apart, electrically conductive tissue sealing surfaces extending along a length thereof, each tissue sealing surface adapted to conduct electrosurgical energy through tissue held therebetween to effect a tissue seal; an insulator disposed between each pair of electrically conductive sealing surfaces; and an electrically conductive cutting element disposed within the insulator of the first jaw member and in general vertical registration with an electrically conductive cutting element disposed within the insulator of the second jaw member, each of the electrically conductive cutting elements including a plurality of peaks offset from a plurality of peaks of the other cutting element, wherein the number of peaks of at least one of the cutting elements is a function of a wavelength of an operating frequency of electrosurgical energy passed therethrough, the cutting elements adapted to electrosurgically effect a tissue cut, wherein the cutting elements are inactive during tissue sealing and the pair of spaced apart electrically conductive sealing surfaces on the first jaw member are energized to a different potential from the corresponding pair of spaced apart electrically conductive sealing surfaces on the second jaw member such that electrosurgical energy can be transferred through the tissue to effect a tissue seal.
 9. An end effector assembly according to claim 8, wherein the plurality of peaks has a period that is a multiple of the operating frequency of the electrosurgical energy.
 10. An end effector assembly according to claim 8, wherein the plurality of peaks of the cutting element of the first jaw member is configured to complement a plurality of valleys interposed between the plurality of peaks of the cutting element of the second jaw member.
 11. An end effector assembly according to claim 8, wherein a number of the plurality of peaks is calculated based on a repetition of the peaks for a predetermined length of the electrically conductive cutting elements.
 12. A method of manufacturing an electrically conductive cutting element adapted to be coupled to an end effector assembly for effecting a tissue cut, the steps comprising: providing an electrically conductive electrode having a predetermined length; and calculating a number of peaks along the predetermined length and a period based on a repetition of the peaks, wherein the number of peaks is a function of an operating frequency of an energy source adapted to supply electrosurgical energy to the electrically conductive cutting element.
 13. A method according to claim 12, wherein the period of the peaks is a multiple of the operating frequency. 